Encapsulated manhole cover

ABSTRACT

Embodiments of the present invention relate to a cover for a manhole or similar structure that encapsulates a traditional cover so as to extend the height of the cover. Generally, a conventional manhole cover is partially or entirely encapsulated in polyurethane to change its outside dimensions to match the environment of an intended location.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a manhole cover and, moreparticularly to an encapsulated manhole cover.

2. Description of Related Art

In many urban areas the benefits of underground utilities requirenumerous manholes and other openings to be provided on the streets andsidewalks. While the manhole and its opening are initially almostunnoticeable, the changing surfaces and environment usually reveal themanholes and other gratings after some time.

For example, FIG. 1 illustrates a conventional manhole coverarrangement. An opening 100 is protected by a manhole cover 102 thatsits on a circular collar 104 that is generally the same height as aroad 106 or other above-ground surface. The design of the collar 104 andcover 102 ensures that the entire arrangement is generally smooth. Forexample, in the roadway environment, the intention is for a vehicle tobe able to pass over the cover 102 with the vehicle's passengers andcargo barely affected.

Over time, however, the road 106 may be re-paved such that its surfacerises far above that of the collar 104. When this occurs, traveling overthe manhole cover can become very uncomfortable and potentially unsafebecause it can damage vehicles or cause drivers to try to avoid them.Municipalities can sometimes be held liable for damage caused by the“potholes” of sunken manhole covers

There have been attempts in the past to address this issue but they haveproven time consuming and expensive. For example, one solution is toextend the collars 104 in some manner such as with supplementary collarsor extension rings to raise the height of the manhole cover; but this islabor and time intensive as well as expensive. Thus, there exists theneed for a way to accommodate the changing elevation of the environmentsurrounding a manhole cover that can be accomplished without expensiveand time consuming construction.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention relate to a cover for a manhole orsimilar structure that encapsulates or partially encapsulates anexisting cover so as to extend the height of the cover. Generally, aconventional manhole cover is partially or entirely encapsulated inpolyurethane to change its outside dimensions to match the environmentof an intended location.

It is understood that other embodiments of the present invention willbecome readily apparent to those skilled in the art from the followingdetailed description, wherein it is shown and described only variousembodiments of the invention by way of illustration. As will berealized, the invention is capable of other and different embodimentsand its several details are capable of modification in various otherrespects, all without departing from the spirit and scope of the presentinvention. Accordingly, the drawings and detailed description are to beregarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects of an encapsulated manhole cover are illustrated by wayof example, and not by way of limitation, in the accompanying drawings,wherein:

FIG. 1 shows a side view of a conventional manhole cover;

FIG. 2 shows a side view of an encapsulated manhole cover in accordancewith the principles of the present invention;

FIG. 3 shows a side cut-away view of the manhole cover of FIG. 2;

FIG. 4 shows an exploded view of a manufacturing method for a manholecover in accordance with the principles of the present invention;

FIG. 5 shows a bottom view of the system of FIG. 5;

FIG. 6 shows another encapsulated manhole cover in accordance with theprinciples of the present invention;

FIG. 7 shows yet another encapsulated manhole cover in accordance withthe principles of the present invention;

FIG. 8 shows a manhole cover capable of being encapsulated in accordancewith the principles of the present invention;

FIG. 9 shows a side-by-side view of different encapsulated manholecovers;

FIG. 10 shows a gasket arrangement useful in cooperation withencapsulated manhole covers in accordance with the principles of thepresent invention; and

FIG. 11 shows another gasket arrangement useful in cooperation withencapsulated manhole covers in accordance with the principles of thepresent invention.

DETAILED DESCRIPTION OF INVENTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various embodiments of theinvention and is not intended to represent the only embodiments in whichthe invention may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof the invention. However, it will be apparent to those skilled in theart that the invention may be practiced without these specific details.In some instances, well known structures and components are shown inblock diagram form in order to avoid obscuring the concepts of theinvention.

As used herein, the phrase manhole cover is meant to encompass a widevariety of covers that are used to cover subterranean openings. Theseinclude manholes to access sewers or other utilities occurring in anylocation. Such openings can particularly occur on a sidewalk or on aroadway where there is vehicle or pedestrian traffic. Additionally, notall such openings are man-sized yet the phrase “manhole cover” is stillused. In some locations, the manhole covers are not always circular butcan also be square or rectangular. Furthermore, conventional manholecovers sometimes are solid and sometimes have openings so that they are“perforated”. All such similar devices are meant to be encompassed bythe phrase “manhole cover” as used herein. Also, the term “encapsulate”is used to encompass both total encapsulation as well as partialencapsulation of a manhole cover which acts as a substrate. As describedbelow, some embodiments contemplate entirely encasing the manhole coverin a material and other embodiments contemplate less than entireencapsulation.

FIG. 2 illustrates a typical urban environment in which a roadway 206has been built up to be far higher than the original collar 104 for amanhole cover. Thus, if a conventional manhole cover were in place, itstop surface would lie far below that of the roadway 206. Mostmunicipalities have some type of guidelines in place which define anacceptable difference between the height of the roadway 206 and that ofthe manhole cover 202. For example, in some cities, the allowabledifference is merely ⅛ inch. The collar 104 generally refers to a basestructure on which the cover 202 rests and may encompass a frame and/ora riser ring.

Embodiments of the present invention contemplate encapsulating aconventional manhole cover in a durable material such as polyurethane soas to add material to the top of the cover so that it's height (orthickness) is increased. Although polyurethane is mentioned as anexemplary material in which to encapsulate a manhole cover, one ofordinary skill will recognize that other materials, such as plastics orpolymers, may be selected based on the expected environment (e.g.,sunlight, temperatures, road chemicals, exposure to oil, gasoline, anddiesel, subject to the weight of various vehicles and potentially struckby snowplows and other equipment.)

As shown in FIG. 2, the encapsulated manhole cover is sized to fit overa collar 104 that was originally in place to support a conventionalmanhole cover. In this example, the cover 202 is circular and,therefore, has an outside circumference matching that of the collar 104.One benefit of this arrangement is that the encapsulated manhole cover202 will have at least two horizontal seating areas 208, 210 and avertical sidewall at which it contacts the collar 104 so as to providestability, to prevent rotation, and to improve its seal. However,contact at both seating areas 208, 210 is not a requirement to practicesome embodiments of the present invention. Additionally, the edge orcorner 201 may be beveled or chamfered, unlike the square corner shownin the figure, to provide a smoother transition with the roadway 206.

The height of the encapsulated manhole cover 202 is determined based onthe environment in which it is to be located. For example, in FIG. 2,two different heights are possible 212 and 214 because the grade of theroadway 206. Although not shown in the figure, four different measuringpoints (e.g., every 90 degrees around a circle) would provide fourdifferent height measurements for the encapsulated manhole cover. Thus,if thought of as a compass, the height of the encapsulated manhole cover202 can vary from one height to another in an East-West direction and aNorth-South direction, respectively.

Thus, one exemplary step of forming the manhole cover 202 of FIG. 2 mayinvolve a person measuring the height of the roadway 206 at variouspoints around the manhole cover. A convenient reference point for suchmeasurements would be a point on the collar 104 which likely wasinstalled level and stable. These measurements can then be recreated ina manufacturing step so that the manhole cover is created with theappropriate contour to match the grade of the surrounding roadway 206.Alternatively, mass manufacturing of “standard” heights could beundertaken so that a user could, for example, procure covers with theclosest “standard” height but which are not further customized to theirexact location. Although, it is feasible to place a “standard” heightcover in place and then grind the surface down to more closely match thesurrounding grade.

In the example above, four different measurement points were used butone of ordinary skill will recognize that fewer or more measurementpoints can be used. Fewer measurements mean that the cover will notmatch the roadway as accurately while more measurements improve accuracybut add time and complexity to manufacturing. Thus, four measurementpoints provide a fair balance between complexity and accuracy.

The resulting encapsulated manhole cover 202 will therefore be properlyseated only when it is oriented so that the proper height areas arelocated adjacent to the correct areas of the roadway 206. To aid aninstaller, the initial measurer may make note of a reference point(e.g., magnetic North) and the manufacturing step can impart a referencemark on the cover 202 that aligns with that reference point that wasmeasured. In this manner, the cover can be properly aligned wheninstalled.

FIG. 3 shows a detailed view of an exemplary encapsulated manhole coverdesigned in accordance with the principles of the present invention. Acover 300 is encapsulated between an upper region 302 and a bottomregion 304 of polyurethane. Although these regions 302, 304 are referredto separately, they are physically all part of the same homogenousstructure that surrounds the cover 300. The cover 300 also includes oneor more holes 306 that allow the polyurethane to bridge from the upperregion 302 to the bottom region 304. These holes 306 can be arranged inany type of pattern but are sufficient to create a structure that willnot de-laminate under the stress of the roadway environment. Althoughthe holes 306 are depicted as having relatively straight side walls,these walls can be sloped as well or otherwise shaped to enhance theadherence of the encapsulating material to the cover 300. The cover 300is traditionally constructed of metal by a foundry but other strongsynthetic materials have recently been used in constructing manholecovers and embodiments of the present invention will work with eithertype of material.

A pick-hole 310 is typically present, but not always necessary, in amanhole cover to aid in its removal from the ground. During the formingprocess of the encapsulating upper region 302, an opening 308 can beformed to provide access to the existing pick-hole 310. This opening 308may beneficially have a flexible flap that prevents debris from enteringthe opening 308 while still allowing access by a tool to the pick-hole310. Manhole covers having through-holes are not usually constructedwith pick holes but because embodiments of the present inventionencapsulate the cover (thus making the through-holes inaccessible) apick hole can be specially constructed in the cover even though italready has through-holes.

FIG. 4 illustrates the principles of manufacturing an encapsulatedmanhole cover according to embodiments described herein. However, manyvaried ways to mold polyurethane are known and can be accomplished withvarious techniques, temperatures, recipes, etc. The present discussionof manufacturing is merely to provide a description of those aspects ofthe encapsulated manholes covers that can be controlled duringmanufacturing.

In FIG. 4, for reference, the cover 300 is flipped so that its top ispointed down. A mold piece 404 is placed on the cover 300 which restsabove another mold piece 402 at a height that determines the thicknessof the region 302 (See FIG. 3). A liquid polyurethane precursor would beadded to the mold and then cured to form the final encapsulated cover.Through the use of customized molds, the top appearance of theencapsulated cover can be customized in appearance. Also, becausepolyurethane adheres well to itself, the molding process can beperformed in multiple steps so that different colors can be used to evenfurther customize the appearance of the cover. For example, amulticolored layer can be applied on top or multiple single color layers(or a mix of the two) such that a subsequent CNC milling step cancustomize the design, color, and appearance of the visible surface ofthe end product. To improve the adherence of the polyurethane to themetal manhole cover, techniques and chemicals are known that etch andcoat the metal to strengthen the bonding between the two materials

A support structure 406 supports the mold 402 and has a variety ofadjustable legs 408, 410, 412. This support structure can be seen inFIG. 5 with four different adjustment points 408, 410, 412, 414. Theseadjustment points can be selected to correspond to the four measurementstaken on site at the intended location. As a result, the encapsulatedcover 202 will have a top surface whose height can vary in at least twodegrees of freedom. Because polyurethane and similar materials arerelatively easy to mill, an alternative manufacturing method would be tomold the encapsulated covers to generally the same height (or a set ofstandard heights) and then customize the height for each cover based onits intended location through a CNC milling operation.

FIG. 6 illustrates additional features of embodiments of the presentinvention. For example, batteries or other electronics 606 can beattached to the bottom of the cover 202. This location will be arelatively dry and safe location so that even sensitive equipment may belocated within a manhole. Other electronic devices 604, either active orpassive, can be encapsulated within polyurethane near the conventionalmanhole cover. This location protects the electronics 604 from theenvironment but offers less interference than if the manhole cover wasmetal and the electronics were located below as previously discussed.There are also items 602 that can be embedded near the surface of theencapsulated manhole cover 202. For example, an identification plate canbe embedded so that each cover has a serial number or other identifyinginformation visible to an observer or an electronic reader. Also, acompass could be embedded which an installer could use, along with anappropriate reference arrow on the cover, to properly align the coverwhenever it is being put back into place.

One of ordinary skill will recognize that a wide variety of items (602,604, 606) can be attached to a manhole cover in this way. Passive oractive RFID tags can be used. GPS location information as well as othertelemetry data can be captured by computerized equipment. For example,the electronics 606 can measure temperature or other environmentalconditions within the manhole and communicate them to other electronics604 that broadcasts them or stores them for later retrieval.

Using ID information (e.g., serial number, ID tags, etc.) a municipalitycan maintain a database that indicates what is intended to be underneatheach manhole. Thus, a utility worker arriving at a site that hasnumerous manhole covers can scan for the appropriate RFID identifier tolocate a desired opening. The sensors 604 can measure road conditions,environment conditions, traffic volumes. Also, through the use ofaccelerometers or GPS devices, the location and movement of manholecovers can be tracked.

Additionally, during the manufacturing, the mold can be shaped so as toform one or more beads 608 around the circumference of the encapsulatedmanhole cover 202. These beads will act as a gasket inside the collarand thus augment the sealing capability of the encapsulated manholecover as well as further reduce the likelihood that the cover willrotate.

FIG. 7 shows an encapsulated manhole cover in which the original cover700 is not entirely encapsulated as in previously described embodiments.In this embodiment, the cover is manufactured in a way that results inthe polyurethane layer 702 encapsulating only the top surface of thecover 700 and extending slightly at a region 704 into the through-holes706. Typically, the depth of the extension region 704 in eachthrough-hole may be as little as ⅛ to ¼ of an inch and still providesufficient strength to help maintain the bond between the polyurethanelayer 702 and the cover 700. One of ordinary skill will recognize thatthe depth of one extension region 704 does not have to equal that of anextension region 704 of a different through-hole. Also, somethrough-holes may be partially filled or fully filled while othersmerely have an extension region 704 around its inside periphery. One ofordinary skill will also recognize that removable plugs may be used inone or more of the through-holes during manufacture so that not everythrough-hole has an extension region 704. For example, using such plugsin half the through-holes will further reduce an amount of polyurethaneconsumed but not adversely impact the bonding strength between the cover700 and the polyurethane 702.

The partially encapsulated manhole cover 710 of FIG. 7 usessignificantly less polyurethane than a similar cover 202 shown in FIG. 2and yet accomplishes the same effect of extending the height of the topof a conventional manhole cover. Also, the additional devices andelectronics described with respect to FIG. 6 can be utilized as well.

An additional method to conserve polyurethane is to use anon-conventionally shaped manhole cover that is specially designed forembodiments of the present invention. The manhole cover 802 can beconstructed of conventional materials and have conventionalthrough-holes 804 but, as can be seen from this cross-sectional view ofFIG. 8, also include unconventional features such as two seats 806, 808and an arched region 810. This unconventional manhole cover 802 can befully encapsulated in polyurethane or can be partially encapsulated inpolyurethane as is shown in FIG. 7 as long as a profile shape ismaintained that appropriately mates with the collar in which theresulting cover will ultimately sit.

The right side of FIG. 9 shows the unconventional cover 802 partiallyencapsulated with polyurethane 902 and seated on the collar 104. Theleft side shows a conventional cover 300 fully encapsulated withpolyurethane 302 also sitting on a collar. As can be seen, the roadway,or outside level, 904 is significantly higher than the top of the collar104. The thickness of polyurethane needed to bring each encapsulatedmanhole cover up to the level 904 is different in each case. Because ofthe two seating surfaces 806, 808 of the unconventional cover 802, itsits higher on the collar 104 and only requires a thickness B ofpolyurethane. The other embodiment with conventional cover 300 requiresa thickness A of polyurethane where A is greater than B.

In the fully encapsulated cover of FIG. 2, the polyurethane at differentlocations around the edge of the encapsulated cover provided ananti-rotation effect as well as helped create a tight seal with acollar. When a cover is partially encapsulated, as in FIG. 7, additionalgaskets may be useful to provide similar benefits, or a cover 710 may beinserted in an opening after a bead of butyl mastic or other sealant hasbeen applied to one or both surfaces that will contact one another.

FIGS. 10 and 11 illustrate various gasket configurations useful with theunconventional cover 802 of FIG. 8. One of ordinary skill will readilyrecognize that a similar, but single, gasket arrangement can also beused for the conventional, partially encapsulated cover 710 of FIG. 7without departing from the scope of the present invention. The partial,cut-away views of these figures show only a cross-section of variousgaskets but it is contemplated that the illustrated gasket would extendaround the periphery of the manhole cover 802 or manhole collar 104.FIG. 10 shows a gasket location 1002 at one of the seating areas of theunconventional manhole cover of FIG. 8 and a second gasket location 1004at the other seating area. Although two gaskets are shown at eachlocation, fewer or even more gaskets could be used as well. Additionalgaskets may be used or thicker gaskets may be used to raise the heightof the entire encapsulated cover so that even less polyurethane 902 isneeded on top of the encapsulated cover in order to match thesurrounding surface 1006. FIG. 11 shows a gasket 1100 having an“Z”-shaped cross section. The thickness 1102 and 1104 should beapproximately equal but the size of the vertical region 1106 can vary soas to match the physical constraints of the intended location which mayvary. As for material, the gasket is beneficially constructed ofurethane, a polymer, rubber, or similar material.

The previous description is provided to enable any person skilled in theart to practice the various embodiments described herein. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments. Thus, the claims are not intended to belimited to the embodiments shown herein, but are to be accorded the fullscope consistent with each claim's language, wherein reference to anelement in the singular is not intended to mean “one and only one”unless specifically so stated, but rather “one or more.” All structuraland functional equivalents to the elements of the various embodimentsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. No claim element is to be construed under the provisions of35 U.S.C. §112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for” or, in the case of a method claim, theelement is recited using the phrase “step for.”

1. An encapsulated manhole cover comprising: an upper region made of afirst material; a substrate, having one or more through-holes, made of asecond material; and a respective extension region located within atleast some of the one or more through-holes and made of the firstmaterial and integrally formed with the upper region; wherein the upperregion and the respective extension region encapsulate at least aportion of the substrate.
 2. The encapsulated manhole cover of claim 1,wherein the respective extension region extends about one-eight toone-fourth an inch into a particular one of the one or morethrough-holes.
 3. The encapsulated manhole cover of claim 1, furthercomprising: a bottom region made of the first material; and a respectivebridging region made of the first material located within at least someof the one or more through-holes and integrally formed with the upperregion and bottom region, wherein the upper region, respective bridgingregion, and bottom region encapsulate the substrate.
 4. The encapsulatedmanhole cover of claim 1, wherein the first material is different thanthe second material.
 5. The encapsulated manhole cover of claim 1,wherein the substrate is a conventional manhole cover.
 6. Theencapsulated manhole cover of claim 5, wherein the second materialcomprises iron.
 7. The encapsulated manhole cover of claim 5, whereinthe second material comprises a composite polymer.
 8. The encapsulatedmanhole cover of claim 1, wherein the first material comprisespolyurethane.
 9. The encapsulated manhole cover of claim 1, wherein anexposed surface of the upper region is customizable in design.
 10. Theencapsulated manhole cover of claim 1, wherein an exposed surface of theupper region is customizable in color.
 11. The encapsulate manhole coverof claim 1, wherein a height of the upper region varies from a firstheight to a different second height along a first direction.
 12. Theencapsulated manhole cover of claim 11, wherein the height of the upperregion varies from a third height to a fourth height along a seconddirection orthogonal to the first direction.
 13. The encapsulatedmanhole cover of claim 1, wherein one or more electronic devices areencapsulated in at least one of the upper region and the bottom region.14. A method of making an encapsulated manhole cover comprising thesteps of: creating a mold comprising: a top region adjacent a top of asubstrate having one or more through-holes; curing polyurethane withinthe mold so as to encapsulate at least the top of the substrate suchthat a respective extension region of polyurethane extends at leastpartially into at least some of the one or more through-holes.
 15. Themethod of claim 14, wherein: the mold further comprises: a bottom regionadjacent a bottom of the substrate; and the step of curing includescuring polyurethane within the top and bottom regions of the mold so asto fill at least some of the through-holes and encapsulate the substratewith polyurethane.
 16. The method of claim 14, wherein the substrate isa conventional manhole cover.
 17. The method of claim 14 furthercomprising the step of: adjusting the top region so that a distance ofan inner surface adjacent the top of the substrate varies at differentpoints with respect to the top surface.
 18. The method of claim 17,wherein first, second, third and fourth points at the periphery of theinner surface have different heights with respect to the top surface.19. The method of claim 18, wherein a first line connecting the firstand second points has a direction orthogonal to a second line connectingthe third and fourth points.
 20. An encapsulated manhole covercomprising: a substrate having a plurality of through-holes; and anencapsulating layer surrounding at least a top surface of the substrateand at least partially filling at least some of the through-holes. 21.The encapsulated manhole cover of claim 20, wherein the encapsulatinglayer surrounds the substrate and fills each of the plurality of throughholes.
 22. The encapsulated manhole cover of claim 20, wherein thesubstrate comprises a conventional manhole cover.
 23. The encapsulatedmanhole cover of claim 20, wherein the encapsulating layer comprisespolyurethane.
 24. The encapsulated manhole cover of claim 20, wherein athickness of the encapsulated manhole cover varies from a first heightto a different second height along a first direction and from a thirdheight to a fourth height along a second direction orthogonal to thefirst direction.